Implantable Neural Interface Device with a Deformable Carrier

ABSTRACT

An improved deformable carrier or connector for an implantable neural interface device is described. The neural interface device comprises a carrier supporting at least one electrode array. The carrier comprises a tubular sidewall extending from a proximal carrier portion to a distal carrier portion. At least one deformable segment is provided in the carrier sidewall.. The deformable segment is more pliable than the remainder of the carrier sidewall to preferably move in response to forces imparted on the carrier and the electrode array by the shifting forces in body tissue. The deformable segment takes the form of a thinned sidewall segment or a slitted wall segment.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication Ser. No. 61/587,606, filed on Jan. 17, 2012.

FIELD OF THE INVENTION

This invention relates generally to the implantable medical devices and,more specifically, to an improved implantable neural interface devicewith a deformable carrier or connector.

BACKGROUND OF THE INVENTION

Conventional carriers or connectors for neural interface devices, suchas those with electrode arrays for deep brain and central nervous systemapplications, have a tendency to “drift” after implantation in targetedtissue. This is due, in part, to the mechanical mismatch between therelatively stiff carrier for the neural interface device and the targetbody tissue and, in part, to tissue regrowth around the neural interfacedevice. Any relative movement between the neural interface device andbody tissue can result in the electrode array moving away from thetargeted tissue. Thus, there is a need in the implantable medical devicefield for an improved carrier or connector for an implantable neuralinterface device. The present invention provides such an improveddeformable carrier or connector for an implantable neural interfacedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1A to 1DC are schematics of a neural interface device 10according to the present invention including a carrier 12, an electricalconductor 20, and a stylet 32.

FIG. 2 is a schematic of the implanted neural interface device 10 havingbeen implanted into body tissue.

FIG. 3 is a schematic of a prior art neural interface device 10A afterhaving been implanted in shifted body tissue.

FIGS. 4 and 4A to 4C are schematics of a first embodiment of the carrier12 for the neural interface device 10 including deformable segments 18.

FIG. 4D is an enlarged view of the area indicted in FIG. 4C.

FIGS. 5A and 5B are schematics of the neural interface device 10 of thepresent invention after having been implanted in shifted body tissue.

FIG. 6 is a schematic of another embodiment of tapered deformablesegments 46 for the carrier 12 of an implantable neural interface device10 according to the present invention.

FIG. 6A is a cross-section along line 6A-6A of FIG. 6.

FIG. 7 is a schematic of anchoring features such as etched recesses 48and through-holes 50 in the carrier sidewall 16.

FIG. 8 is a schematic of an electrode array 14.

FIGS. 9A to 9B are schematics of another embodiment of a deformableconnector 102 for a neural interface device 100 according to the presentinvention.

FIGS. 10A to 10D are schematics of a method of manufacturing the neuralinterface device 100 illustrated in FIGS. 9A and 9B.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, FIGS. 1 and 1A to 1C illustrate a preferredembodiment of an implantable neural interface device 10 according to thepresent invention. The neural interface device 10 is implantable into awide variety of body tissue including the brain, spinal cord, peripheralnerve, muscle, and/or any suitable neural tissue and comprises a carrier12 supporting at least one electrode array 14.

The electrode array 14 may be made from a thin-film polymer substratesuch that there is a high density of electrode sites at a first end ofthe array (e.g., the distal end) and bonding regions at a second end ofthe array (e.g., the proximal end). The polymer substrate is preferablyparylene, polyimide, silicone or a suitable combination of organic andinorganic dielectrics, but may additionally and/or alternatively be madeof any suitable material. The substrate can also include a dielectriclayer comprised of silicon nitride, silicon dioxide, silicon carbide,and mixtures thereof.

The carrier 12 is preferably of silicone or polyurethane and comprises atubular sidewall 16 having a length extending from a proximal carrierportion 12A to a distal carrier portion 12B. The distal carrier portion12B has a step 12C transition to a thin-walled distal end 12D. The step12C has a height that substantially matches the thickness of the thinfilm substrate comprising the electrode array 14. That way, theelectrode assay 14 is wrapped and otherwise supported at least part wayaround the circumference of the distal carrier end 12D to provide asmooth transition to the distal carrier portion 12B. To facilitateadhesion between the carrier 12 and electrode array 14, smallnon-homogenous perforations may be micromachined into the thin-filmsubstrate to allow for the material of the carrier 12 to form a robustanchor with the electrode array 14.

At least one deformable segment 18 is provided along the length of thecarrier 12 intermediate a first carrier sidewall portion 16A and asecond carrier sidewall portion 16B. As will be described in greaterdetail, hereinafter, the deformable segment 18 is a portion or locationalong the carrier 12 that is compressible, tensile, articulatable,and/or rotatable along an axis thereof, such as a longitudinal axis ofthe carrier. Compression or extension of the deformable segment 18results in translation of the carrier sidewall portions 16A, 16Brelative to one another along an axis of insertion (e.g., longitudinalaxis along the carrier). However, the deformable segment 18 mayadditionally and/or alternatively bend or rotate or deform in any othersuitable manner along any suitable axis. For instance, the deformablesegment 18 may bend or curve to enable the sidewall portions 16A, 16B tobecome axially misaligned or curved along the length of the carrier 12.In an alternative embodiment, the entire length of the carrier 12 issubstantially equivalent to a deformable segment 18 such that thecarrier is adapted to deform in compression, extension, and/or any othersuitable manner.

An electrical conductor 20 extends from the proximal carrier portion 12Ato the distal carrier portion 12B where the conductor electricallyconnects to at least one electrode site 22 of the electrode array 14supported by the distal carrier end 12D. As will be described in greaterdetail hereinafter, the electrode site 22 is exemplary of a stimulationelectrode configured for electrical stimulation of body tissue or arecording electrode for recording of physiological data from bodytissue. In that respect, the novel carrier 12 facilitates insertion orimplantation of the electrode array 14 into body tissue and, onceimplanted, helps mitigate or eliminate drift (movement) of the implantedelectrode array 14 within the tissue.

The conductor 20 preferably has coiled or otherwise stretchable ordeformable sections 20A that coincide with the deformable segments 18 inthe carrier 12 of the neural interface device 10. The conductor 20 ispreferably a thin-film structure containing multiple individuallyconductive traces, but may be a wire or any suitable conductivematerial. The conductor 20 may be wound around the external surface ofthe carrier 12, wound within a wall of the carrier, or wound around aninternal surface of the carrier. The coiling or winding density ispreferably selectively varied along the length of the carrier 12 tomodulate the flexibility of the conductor 20. In a preferred embodiment,the conductor 20 include at least one section of lower coiling densitycorresponding to or aligned with a deformable segment. 18 and at leastone section of higher coiling density corresponding to or aligned withone of the carrier sidewall section 16A, 16B. In that manner, thecarrier 12 and coiled conductor 20 may be deformable in tandem incompression, tension or extension, articulation, rotation and/or anysuitable manner.

FIG. 2 is a schematic illustration of the neural interface device 10according to the present invention extending through the cranium 24 andinto brain tissue. This drawing shows that brain tissue is notnecessarily homogenous. For example, the brain tissue is depicted ascomprising tissue layers or regions 26A, 26B and 26C. The neuralinterface device 10 has been implanted into the brain tissue with theelectrode array 14 residing at a target tissue site 28.

Over time, regions of brain matter can become compressed or expandedthrough tissue changes. A tethered connection of the neural interfacedevice to the cranium or other proximal structures may inducedisplacement as well. Such non-specific movement of body tissue candisplace an implanted electrode array away from the targeted tissue 28.FIG. 3 shows that relative shifting has occurred between the varioustissue layers or regions 26A, 26B and 26C. This shifting results in theelectrode array 14A of a prior art neural interface device 10A no longerresiding at the target tissue site 28. The consequence can be diminishedor even completely ineffective neural stimulation, which is undesirable.

The carrier 12 of the present neural interface device 10 is preferablyat least partially made of a flexible material, such as an elastomer.Nitinol is another preferred material for the carrier 12. The carrier 12is preferably tubular with a substantially cylindrical inner surface andincludes one or more lumens 30 (FIG. 1A), such as for receiving a stylet32 (FIG. 1C) therein. The stylet 32 has a pointed tip at its distal end32A that helps facilitate insertion of the neural interface device 10into tissue. If desired, the stylet 32 can have a lumen 34 fortransporting fluids or serving as a passage for moving other devices(not shown) through the stylet/carrier assembly from the proximalcarrier portion 12A to the distal carrier portion 12B and out the styletend 32A thereof.

The stylet 32 may be adapted to remain in the tissue coupled to thecarrier 12 and include deformable segments 36 similar to those 18 of thecarrier 12 that enable compression and/or extension. If provided, thedeformable segments 36 of the stylet 32 are preferably aligned withthose of the carrier 12. That is so compression and extension of thestylet. 32 and carrier 12 correspond to each other. Alternatively, thestylet 32 may be adapted for removal from the carrier 12 afterimplantation of the neural interface device 10 into body tissue.

FIGS. 4 and 4A to 4C illustrate a first embodiment of a carrier 12according to the present invention. As previously described, the carrier12 comprises the tubular sidewall 16 with a substantially cylindricalinner surface having one or more deformable segments 18 provided atspaced locations along its length. More specifically, the tubularsidewall 16 comprises a plurality of relatively less deformable carriersidewall portions 16A, 16B, 16C, 16D and 16E, etc. spaced apart fromeach other by deformable segments 18. The less deformable sidewallportions 16A to 16E each have a first wall thickness that issubstantially uniform around the annular extent thereof. This isillustrated in the cross-sections of FIGS. 4A and 4C.

As shown in the cross-sections of FIGS. 4B and 4C, the deformablesegments 18 are provided by an annular thinning of the wall thickness.As shown in FIG. 4D, the exemplary deformable segment 18 shown in FIG.4C has a radiused curvature 38 from where it connects to proximalsidewall segment 16A and to distal sidewall segment 16B. That is theradiused curvature of the deformable segment has a cross-section along aplane aligned perpendicular to a longitudinal axis of the carrier 16that meets the proximal carrier portion 16A of the first wall thicknessand curves to a trough having a second wall thickness at about amid-point to a distal carrier portion 16B of the first wall thickness.In other words, the carrier segments 16A to 16E, etc. generally have afirst wall thickness and the deformable segments 18 generally have asecond wall thickness that is less than the first wall thickness.

According to the first embodiment, the carrier 12 is of a continuousmolded tubular construction with the thinned deformable segments 18characterized as a mechanically thinning of the sidewall 16. Thinning ofthe sidewall can be done by any one of a number of methods includingturning the carrier 12 on a lathe, by selective heat pressing thesidewall 16, and the like. Moreover, the carrier sidewall segments 16Ato 16E and the deformable segments 18 can be separately manufactured andthen serially connected together by thermal sealing, epoxy, or anysuitable sealing or coupling method.

As shown in FIG. 5A, the deformable segments 18 enable the carrier 12and the supported electrode array 14 to remain in the correct positionand orientation with respect to the targeted tissue 28. The deformablesegments 18 are more pliable than the remainder of the carrier sidewall16 to preferably move in response to forces imparted on the carrier 12and the electrode array 14 by the tissue. As shown in FIG. 5A, thedeformable segments 18 enable the carrier 12 to more in compression andextension 40. FIG. 5B shows that the deformable segment 18 enables thecarrier 12 to undergo both bending 42 and rotational 44 movement. Asused herein, the term pliable in reference to the deformable segments 18means easily bent, relatively more flexible, or relatively suppler.

FIG. 6 illustrates that a deformable segment 46 does not necessarilyrequire the radiused curvature 38 shown for deformable segment 18 inFIGS. 4C and 4D. Instead, the deformable segment 46 can have anirregular or graduated cross-sectional shape that is thinnest at aproximal end 46A and gradually thickens as the segment extends to adistal segment end 46B connected to the next carrier sidewall segment16B. There can also be a number of deformable segments 46 connectedend-to-end intermediate the carrier sidewall segments 16A and 16B.Moreover, the irregularly-shaped deformable segment 46 can be reversedto that shown in FIG. 6. That would be where the segment 46 is thickestat the proximal carrier sidewall segment 16A and thins as it extends tothe next, more distal carrier sidewall segment 16B.

In another embodiment, the deformable segments 18 are made of a moreflexible material or overall composite of materials having a lowerelastic modulus than the carrier segments 16A to 16E, etc. For example,the carrier sidewall segments are of a polymeric material having adurometer ranging from about 75 A to about 60 A, more preferably of apolymeric material having a durometer ranging from about 70 A to about55 A. Then, the deformable segments 18, 46 are of a more flexiblepolymeric material having a durometer ranging from about 50 A to about25 A, more preferably from about 45 A to about 30 A.

In one embodiment, the carrier sidewall 16 is of a first polymericmaterial having a durometer ranging from about 75 A to about 60 A andthe deformable segment 18 is of a second polymeric material having adurometer ranging from about 50 A to 25 A. Moreover, the carriersidewall 16 of the first polymeric material and the deformable segment18 of the second polymeric material have similar thicknesses.

In some embodiments, as shown in FIG. 7, the carrier may include one ormore anchoring features, such as an etched recess 48 or a through-hole50 in the carrier sidewall 16. The anchoring features 48, 50 may helppromote tissue regrowth into the carrier structure, thereby improvinganchoring of the carrier and/or first electrical subsystem in tissue.The carrier sidewall 16 may also be selectively coated with adhesionpromoting factors, such as laminin, fibronectin, L1 molecule (Azemi,Gui. 2011, Biomaterials), etc., to promote tissue adhesion.

The electrode array 14 is adapted to provide dynamic tunable electricalinteraction with body tissue, and preferably includes a plurality ofrecording (e.g., sampling or mapping) and/or stimulation electrodesites. For example, the neural interface electrode array may beconfigured to provide stimulation ranging from macroscale specificity tomicroscale directional patterning.

As shown in FIG. 8, one embodiment of the electrode array 14 includessixty-four stimulation electrodes 52 and thirty-two recording electrodes54 positioned axially along and circumferentially around the carrier 12.Each stimulation site 52 has a surface area of approximately 0.196 mm²(diameter approximately 500 μm), but may alternatively have any suitablesurface area. Each recording site 54 has a surface area of approximately0.00196 mm² (diameter approximately 50 μm), but may alternatively haveany suitable surface area. The stimulation sites 52 are positioned suchthat four sites are equally distributed around the carrier circumferencewith a center-to-center spacing of approximately 750 μm, and distributedin 16 successive rows equally distributed along the longitudinal oraxial direction of the carrier with a row-to-row spacing ofapproximately 750 μm. A pair of recording sites 54 is positioned onopposite sides of the carrier 12 between each row of stimulation sites52. Each pair of recording sites 54 is rotated 90 degrees around thecarrier with respect to an adjacent pair of recording sites. Inalternative embodiments, the electrode array 14 may include any suitablenumber of stimulation electrode sites 52 and recording sites 54 arrangedin any suitable manner.

In another embodiment, the electrode array 14 includes a plurality ofcylindrical electrodes (not shown) spaced apart from each other axiallyalong the length of the carrier 12. The cylindrical electrodes can beused in monopolar or bipolar modes to deliver approximately sphericalpotential fields from separate locations along the cylindrical carrier.Furthermore, although the carrier 12 is preferably a single tube,alternative embodiments may have any suitable shape, such as withbranches or forks.

FIGS. 9 and 10 illustrate another preferred embodiment of a neuralinterface device 100 according to the present invention. The implantableneural interface device 100 comprises a flexible ribbon-type connector102 having a length extending from a first, proximal connector end 102Ato a second, distal connector end 102B, and a width extending between athird, right edge 102C and a fourth, left edge 102D. Further, theconnector has a fifth, upper surface 102E spaced from a sixth, lowersurface 102F by a thickness 102G (FIGS. 10A to 10C). The ribbon-typeconnector 102 is preferably of a flexible polymer-based cable, such asof silicone or polyurethane, but may alternatively be any other suitableplanar material. Preferably, the connector 102 is encased in silicone oranother suitable biocompatible material.

The connector 102 includes at least one deformable segment 104 thatfunctions in a similar manner as previously described with respect tothe deformable segments 18, 46 of the carrier 12. The deformable segment104 comprises at least one split 106 that extends from a proximalslitted end 106A to a distal slitted end 106B. The slit 106 is where thematerial of the ribbon-type connector 102 has been cut completelythrough its thickness 102G so that open space exists between adjacentstrands 108 of the connector material. The slit 106 and, consequently,the open space extends from a proximal end 104A of the deformablesegment to a distal end 104B thereof. More preferably, a plurality ofslits 106 form a plurality of strands 108 along the length of thedeformable segment 104. Each strand 108 is narrower and consequentlymore flexible than the unslit connector 102 and includes at least oneconducting trace (not shown), and the like, extending from the first,proximal connector end 102A to the second, distal connector end 102Bwhere the traces electrically connect to at least one electrode cite 22of the previously described electrode array 14.

In this embodiment, the connector 102 with the deformable segment 104may be fabricated using MEMS or a roll-to-roll technique, and alithographic technique may be used to pattern the conductive traces. Forinstance, masking and etching techniques may be used to etch throughspecific regions of the planar connector 102 to form the one or moresplit 106. The number of splits 106 and their individual widths may bedependent on various factors, such as intended tissue anatomy of aspecific application and manufacturing cost.

FIGS. 10A to 10D illustrate the connector 102 including the deformablesegment 104 may include an undulating or three-dimensional shape 110.Undulations 110 facilitate an additional amount of linear expansion orcontraction before the connector 102 reaches the tension or compressionlimits inherent in its material. The undulations 110 may be formed inboth a slit and unslit portion. In that respect, the undulations 110 inthe connector 102 may be formed by placing the planar structureconnector 102 shown in FIG. 10A between complementary undulating top andbottom molds 112A and 112B, and applying heat 114 to anneal thestructure. As shown in the side view of FIG. 10C and top plan view ofFIG, 10D, the thusly conditioned connector 102 has undulations 110mirroring those of the molds 112A, 112B. Although FIGS. 10A to 10Dprimarily show undulations 110 along the axial direction of theconnector 102, the connector may additionally and/or alternatively haveundulations along the lateral direction or across the width extendingfrom right edge 102C to left edge 102D thereof, or any suitabledirection.

If desired, the planar connector 102 can be formed into a tubular shape.

The deformable segments 18, 46 of the neural interface device 10 and thedeformable segment 104 of the neural interface device 100 preferablyhave lengths of from about 0.5 mm to about 2 mm. Moreover, when there ismore than one of them in a neural interface device, they are spacedabout 1 mm to about 5 mm from each other.

The proximal ends of the implantable neural interface devices 10, 100are connectable to a second electrical subsystem (not shown) thatfunctions to operate with the electrode array 14. For example, thesecond electrical, subsystem may be a printed circuit board with orwithout on-board integrated circuits, comprise an on-chip circuitry forsignal conditioning, filtering, or stimulus generation, be anApplication Specific Integrated Circuit (ASIC), a multiplexer chip, abuffer amplifier, an electronics interface, an implantable pulsegenerator, an implantable rechargeable battery, integrated electronicsfor real-time signal processing of the commands sent to the stimulationelectrodes 52 or received from the recording electrodes 54, integratedelectronics for control of any fluidic components, and any othersuitable electrical subsystem.

In one embodiment, the neural interface devices 10, 100 second may becoupled to a fixation point within the cranium of a patient. Forexample, a cranial chamber may be attached to the skull, preferably in acranial burr hole, of a patient, and one or more of the neural interfacedevices 10, 100 may be coupled to the cranial chamber. One embodiment ofsuch a cranial chamber may be similar to that described in U.S. Pat. No.7,548,775, which is incorporated in its entirety by this reference. Theneural interface devices 10, 100 may further include one or more fluidicchannels that provide for delivery of a fluid (e.g., therapeutic drugs)to inhibit biologic response to the implant or to elicit a therapeuticresponse.

Some embodiments of the neural interface devices 10, 100 of the presentinvention may include any combination of any of them. One portion of aneural interface device may comprise features of neural interface device10 while other portions may include features of the neural interfacedevice 100. Moreover, the deformable segments 18, 46 and 104 may beregularly or irregularly spaced along the length of a neural interfacedevice. For example, it may be desirable to impart greater flexibilityto selected regions of the carrier, such as spacing the deformablesegments progressively closer together towards a distal end or aproximal end of the carrier. Some of the deformable segments mayadditionally and/or alternatively be more easily deformed than otherdeformable segments, which may further provide greater flexibility toselected regions of the neural interface device.

A person skilled in the art will recognize from the previous detaileddescription including the drawing figures, that modifications andchanges can be made to the preferred embodiments of the presentinvention without departing from the scope of the invention defined inthe following claims.

What is claimed is
 1. A neural interface device, which comprises: a) acarrier having a carrier sidewall extending along a first length from acarrier proximal end to a carrier distal portion having a distal end,wherein the carrier proximal end is electrically connectable to amedical device; b) at least one electrode supported on the distalcarrier portion, wherein the electrode is configured for at least one ofelectrical stimulation of body tissue and sensing of physiologicalcharacteristics of the body tissue; c) an electrical conductor thatextends along the carrier from the carrier proximal end to the carrierdistal portion where it is electrically connected to the electrode; andd) a deformable segment of the carrier sidewall at an intermediatelocation between the carrier proximal end and the carrier distal end,wherein the deformable segment is relatively more pliable than theremainder of the carrier sidewall.
 2. The neural interface device ofclaim 1 wherein the carrier is of a polymeric material.
 3. The neuralinterface device of claim 1 wherein the carrier has a tubular structure.4. The neural interface device of claim 1 wherein the carrier sidewallhas a first wall thickness and the deformable segment has a second wallthickness that is less than the first wall thickness.
 5. The neuralinterface device of claim 4 wherein the deformable segment is a radiusedcurvature recessed into the first wall thickness of the carrier.
 6. Theneural interface device of claim 5 wherein the radiused curvature of thedeformable segment extends around the annular extent of the carriersidewall.
 7. The neural interface device of claim 1 wherein the radiusedcurvature of the deformable segment has a cross-section along a planealigned perpendicular to a longitudinal axis of the carrier that meets aproximal carrier portion of the first wall thickness and curves to atrough having a second wall thickness at about a mid-point to a distalcarrier portion of the first wall thickness.
 8. The neural interfacedevice of claim 1 wherein the deformable segment has a graduatedthickness that is thinnest at a proximal end of the segment and thickensas the deformable segment extends distally.
 9. The neural interfacedevice of claim 8 wherein the graduated thickness of the deformablesegment extends around the annular extent of the carrier sidewall. 10.The neural interface device of claim 1 wherein the deformable segmenthas a graduated thickness that is thinnest at a distal end of thesegment and thickness as the deformable segment extends proximally. 11.The neural interface device of claim 10 wherein the graduated thicknessof the deformable segment extends around the annular extent of thecarrier sidewall.
 12. The neural interface device of claim 1 whereinthere are at least two deformable segments at spaced locations along thefirst length of the carrier.
 13. The neural interface device of claim 1wherein the electrical conductor is relatively more stretchable at alocation coinciding with the deformable segment of the carrier.
 14. Theneural interface device of claim 1 wherein the carrier sidewall has asubstantially cylindrical inner surface.
 15. The neural interface deviceof claim 1 wherein the at least one electrode is supported on asubstrate of a material selected from the group consisting of parylene,polyimide, silicone, silicon nitride, silicon dioxide, silicon carbide,and mixtures thereof.
 16. The neural interface device of claim 1 whereinthe distal portion of the carrier has a step transition to a thinnercarrier sidewall portion that is sized to support the electrodesupported on the polymeric substrate,
 17. The neural interface device ofclaim 1 wherein the deformable segment is compressible, tensile,articulatable, and rotatable.
 18. The neural interface device of claim 1wherein the carrier sidewall of the first wall thickness is of a firstpolymeric material, having a durometer ranging from about 75 to about 60and the deformable segment of the second wall, thickness is of a secondpolymeric material having a durometer ranging from about 50 to about 30.19. The neural interface device of claim 18 wherein the first and secondpolymeric materials are the same or different.
 20. The neural interfacedevice of claim 1 wherein the carrier sidewall is of a first polymericmaterial having a durometer ranging from about 75 to about 60 and thedeformable segment is of a second polymeric material having a durometerranging from about 50 to
 30. 21. The neural interface device of claim 20wherein the carrier sidewall of the first polymeric material and thedeformable segment of the second polymeric material have similarsidewall thicknesses.
 22. The neural interface device of claim 1 whereinthe carrier is of silicone or polyurethane.
 23. The neural interfacedevice of claim 1 wherein the deformable segment has a length of fromabout 0.5 mm to about 2 mm.
 24. The neural interface device of claim 1wherein there at least two deformable segments spaced apart along thefirst length of the carrier and the deformable segments are from about 1mm to about 5 mm from each other.